Research on the Construction of in situ Tumor Vaccine Based on Guanidino-modified Oligo-chitosan and its Anti-tumor Activity

JIANG Yun-shan; XU Hao-xin; XIE Li-qing; GUO Bao-ling; LIU Peng-fei

Abstract：Objective: This study aims to explore the potential of an in situ tumor vaccine based on guanidine-modified oligo-chitosan in anti-tumor immunity by constructing such a vaccine, and to provide a theoretical basis for the development of novel tumor immunotherapy strategies. Methods: Chitosan was degraded into oligo-chitosan by cellulase method. Guanidine-modified oligo-chitosan was synthesized using dicyandiamide, and then loaded with polyinosinic acid-polycytidylic acid (PIC) and mammalian target of rapamycin (mTOR) small interfering RNA to prepare in situ tumor vaccine nanoparticles. The expression level of mTOR protein, cell invasion, and proliferation in B16F10-OVA cells treated with different components were observed. B16F10-OVA tumor-bearing mice were prepared and divided into 5 groups. Normal saline (NC), chitosan (CHI), oligo-chitosan (COS), guanidine-based modified oligo-chitosan (GBM-COS), and nanoparticles (guanidine-modified oligo-chitosan in situ tumor vaccine, GBM-COS+PIC+mTOR) were respectively injected into the tumor sites. The tumor inhibition rate, infiltration and functional changes of immune cells in tumor tissues and draining lymph nodes, and survival period of the mice were observed. Results: In the GBM-COS+PIC+mTOR group, the expression level of mTOR protein in tumor cells was downregulated, and the cell proliferation rate and invasion rate were significantly lower than those in the other four groups (P<0.05). The tumor volume inhibition rate, DC infiltration proportion, macrophage activation level, CD8+T cell proportion, and survival time in the B16F10-OVA tumor-bearing mouse model of the GBM-COS+PIC+mTOR group were all higher than those in the other four groups (P<0.05). Conclusion: The guanidine-modified oligo-chitosan-based nanoparticles exhibited good anti-tumor activity both in vitro and in vivo, which can provide a new candidate method for novel tumor immunotherapy by inducing immunogenic cell death (ICD) and activating immune cells.